Conventional imaging systems, such as photographic cameras and video cameras, can be reduced in size by miniaturizing the components that comprise the imaging systems. This method of constructing smaller and more compact imaging systems is inherently limited by the capability of manufacturing and assembling smaller components. In general, as imaging systems are reduced in size, the resolving capability of the imaging systems are also reduced.
Resolution determines the highest amount of image detail that can be captured in a scene and is fundamentally limited by the aperture size of the optical system (see Introduction to Fourier Optics by Joseph W. Goodman, McGraw-Hill Electrical and Computer Engineering Series, second edition, 1996, pp. 134-144). One calculation of resolution relates the aperture size to the highest nonzero spatial frequency of the modulation transfer function (MTF). An imaging system with a smaller aperture size, therefore, will capture images at lower resolution than an imaging system with a larger aperture size.
European Patent Application No. 1 079 613, by Jun Tanida et al. filed Aug. 18, 2000, titled “IMAGE INPUT APPARATUS” uses an array of lenses to form a compact imaging system. The method of Tanida et al. uses a partitioned wall layer between the array of lenses and a photosensitive element array to form an image. The resolution of the images collected by Tanida et al. is limited to the size of the individual lenses because Tanida et al. do not disclose a method of relaying all of the light captured by the array of lenses onto one photosensitive element.
A plurality of imaging elements can be combined in geometrical patterns to form a larger aperture that can capture an image with a higher resolution than possible with an image captured from a single imaging element. Multiple aperture system concepts, that coherently combine the light collected from a plurality of apertures to form a higher resolution image, have been disclosed in prior art. U.S. Pat. No. 5,905,591, issued May 18, 1999, to Alan L. Duncan et al., titled “MULTI-APERTURE IMAGING SYSTEM,” uses multiple telescopes to synthesize a larger aperture for a space-based deployable imaging system. In another example, U.S. Pat. No. 5,919,128, issued Jul. 6, 1999, to Joseph P. Fitch, titled “SPARSE APERTURE ENDOSCOPE,” combines fiber optic light pipes to form an endoscope.
There is a need, therefore, for a compact imaging system using a plurality of apertures that can potentially capture an image resolution comparable to that of a large single aperture.